Minecraft Pe Pocket Inventory Editor 21
edit: I have potentially found a solution. After logging into my Win 10 minecraft with the glitched marketplace I closed the game. Next I logged onto my same microsoft account on my phone. It sucessfully logged in with a working marketplace, and then I closed the mobile version. I then booted up the Win 10 version, and after a slightly longer load time it booted it up with a working marketplace/skin editor. I have not had the problem on other platforms, but it could be caused by having an account active/not-active on multiple devices.
Minecraft Pe Pocket Inventory Editor 21